The present invention relates to a lockset for use in a door, and particularly to a door-mounted cylindrical lockset having a chassis for mounting in the door, a door handle coupled to a door latch-operating mechanism housed in the chassis, and a rose assembly anchored to the door and arranged to cover the connection between the door handle and the door latch-operating mechanism. More particularly, the present invention relates to an anti-rotation mechanism for locking the chassis to the anchored rose assembly to anchor the chassis to the door.
Cylindrical lockets are well known. See, for example, U.S. Pat. No. 3,955,387 to Best et al; U.S. Pat. Nos. 4,424,691 and 4,437,695 to Foshee; and U.S. Pat. No. 4,920,773 to Surko, Jr. A cylindrical lockset connects a door handle to a retractable latch bolt mounted in a door so that the door handle can be turned to retract the latch bolt and unlatch the door. Typically, a cylindrical lockset is mounted in a lockset-receiving aperture provided in a door.
The latch bolt is mounted for sliding movement in a horizontal passage formed in the door. The horizontal passage has a first opening at one end in a vertical edge of the door and a second opening at the other end communicating with the lockset-receiving aperture formed in the door. The latch bolt is normally biased by a spring to a projected position latching the door. The latch bolt is moved against the spring to a retracted position inside the horizontal passage by the cylindrical lockset once the door handle is turned properly by a user.
Each cylindrical lockset includes various mechanical linkages and locking mechanisms mounted inside the lockset-receiving aperture formed in the door and used to control operation of a latch bolt retractor coupled to the latch bolt. An outer portion of the cylindrical lockset carries an outside door handle (e.g., knob or lever arm) and an inner portion of the cylindrical lockset carries an inside door handle.
To open a door, a user can turn either the inside or outside door handle to operate the mechanical linkage mounted inside the cylindrical lockset. This action enables a user to retract a spring-biased latch bolt mounted in the horizontal passage and connected to the cylindrical lockset from a projected position extending beyond the vertical edge of the door and engaging a side slot formed in a door jamb to a retracted position inside the door. The user is now free to swing the door on its hinges from a closed position to an opened position.
A lever-handled lockset is susceptible to "overtorquing" damage during an attack. If an intruder applies excessive torque to a locked cylindrical lockset, in some cases, the intruder can break or damage the lockset by rotating the lockset chassis. The chassis is typically mounted in the lockset-receiving aperture formed in the door and configured to hold a door latch-operating mechanical linkage in place in the door. By forcibly rotating the lockset chassis, the intruder may be able to damage the lockset enough to break the lock mechanism in the lockset and open a previously locked door.
It is known to provide a mechanism in a lockset for blocking rotation of the lockset chassis in the door. See, for example, U.S. Pat. Nos. 3,955,387 to Best; 4,604,879 to Neary; 4,869,083 to DeMarseilles; and 5,149,155 to Caeti.
What is needed is a sturdy anti-rotation mechanism for locking a lockset chassis in a door against rotation during an attack on the lock by an intruder. Security personnel would appreciate an improved lockset chassis anti-rotation mechanism that is configured to minimize chassis rotation by strengthening the connection anchoring the chassis to the door. By minimizing chassis rotation during an attack on the lockset, overtorquing damage to the lockset can be minimized.
According to the present invention, a lockset chassis assembly includes a rotatable latch-operating spindle, a chassis supporting the spindle, a rose engaging the chassis and surrounding the spindle, and a locking pin engaging the chassis and the rose to block rotation of the chassis relative to the rose about the longitudinal axis of the spindle. The rose can be anchored to a door in which the lockset chassis assembly is mounted.
A chassis keyway is formed in the chassis and a rose keyway is formed in the rose and these two keyways cooperate to define a locking pin-receiving port therebetween. The locking pin passes through this port and engages both the chassis and the rose. Such engagement functions to lock the chassis to the rose (which is anchored to the door) to block unwanted rotation of the chassis relative to the door during an attack on the lockset.
In preferred embodiments, the chassis includes an outer hub coupled to an inner hub to position a latch retractor assembly therebetween. Also, an outer rose is mounted on the outer hub and an inner rose is mounted on the inner hub. The outer hub includes a threaded outer surface for rotatably engaging threads formed in a central aperture provided in the outer rose. The inner hub also includes a threaded outer surface for receiving the inner rose.
Illustratively, the inner and outer hubs are each formed to include one portion of the chassis keyway. An inner portion of the chassis keyway is an axially extending channel that has a half-round shape and is formed in the inner hub to interrupt the threaded outer surface in the inner hub. An outer portion of the chassis keyway also is an axially extending channel that has a half-round shape and is formed in the outer hub to interrupt the threaded outer surface in the outer hub. When fully assembled, an axially outer end of the locking pin lies in the half-round channel formed in the outer hub, an axially inner end of the locking pin lies in the half-round channel formed in the inner hub, and a middle section of the locking pin passes over the latch retractor assembly that is mounted to lie between the spaced-apart inner and outer hubs.
In use, when torque is applied to an outer door handle mounted on the latch-operating spindle, the torque is transmitted through the chassis to the locking pin and the outer rose (which is anchored in a fixed position to the door) to stop the chassis from rotating. Thus, the lockset chassis is protected from overtorquing damage during an attack. The locking pin is made of steel and has a head portion at its axially inner end and an outer rose-engaging foot portion at its axially outer end. The outer rose-engaging foot portion lies in a first half-round keyway formed in the outer hub and adjacent to the outer rose and the head portion lies in another half-round keyway formed in the inner hub and aligned in collinear relation with the first half-round keyway.
The inner and outer hubs are preferably investment castings made of steel. The outer rose includes a rose liner that is a stamped steel part that screws onto the outer hub and defines the rose keyway and a shell-like rose cover that surrounds the door handle shaft and mounts on the rose liner. When the rose keyway on the outer rose and the outer portion of the chassis keyway on the outer hub are in alignment facing one another, the locking pin is biased by a compression spring into the locking pin-receiving port defined by those two keyways to lock the chassis to the outer rose, thereby blocking rotation of the chassis relative to the door. Illustratively, the compression spring is carried on the locking pin and positioned to lie between the inner and outer hubs. The rose liner is stopped from rotating relative to the door by steel studs that are riveted onto the rose liner and protrude into holes that have been drilled out in the door.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.